This application is based on Japanese Patent Application No. 10-178790, filed Jun. 25, 1998, the contents of which are incorporated herein by reference.
The present invention relates to a display control apparatus and interlaced data display control method and, more particularly, to a display control apparatus for displaying interlaced display image data such as a moving image on a display device used as a display monitor for a computer, and an interlaced data display control method.
In recent years, upon developments of computers and multimedia techniques, a variety of so-called multimedia computer systems have been developed. A computer system of this type has a function of playing back moving image and audio data in addition to text and graphics data.
With the advent of such multimedia computers, recently, a DVD is receiving a lot of attention as a new medium that takes the place of a CD-ROM. A DVD-ROM medium can record data around 4.7 Gbytes on one side, which is about seven times the capacity of the existing CD-ROM, and around 9.4 Gbytes on two sides. Using this DVD-ROM medium, a title such as a movie which contains a large volume of video information can be played back with high image quality.
The contents of a DVD are decoded by a DVD decoder, and are output as 60-Hz field data for interlaced display, which corresponds to an NTSC output.
When such data are displayed on a display monitor of a computer, the interlaced display data output from the DVD decoder must be converted into noninterlaced display data. The interlace to noninterlace conversion is done by a display controller that controls the display monitor.
The interlace to noninterlace conversion by the display controller is normally done using simple field combination. That is, one frame is generated by superposing even and odd fields on a frame memory, and is noninterlaced-displayed on the display monitor of the computer.
However, when the interlace to noninterlace conversion using such simple field combination is made, fields having a time difference are combined into a single frame, and so-called feathering occurs, i.e., an edge forms a stripe pattern. This phenomenon is especially conspicuous in a scene with fast motions.
It is an object of the present invention to provide a display control apparatus and interlaced data display control method, which can display a smooth image free from feathering on a display monitor of a computer, and can display interlaced data such as a moving image, which is created for a TV, with high quality.
In order to achieve the above object, according to the present invention, an apparatus comprises: input means for inputting interlaced data; and noninterlaced data generation means for generating noninterlaced data by appending interlaced data of a predetermined color to the interlaced data input by the input means.
In this display control apparatus, interlaced data of a predetermined color is appended as dummy data to the input interlaced data to generate pseudo noninterlaced data. The pseudo noninterlaced data is noninterlaced-displayed on the display device. In this way, since the input interlaced data mimics noninterlaced data upon appending dummy data, feathering resulting from combination of fields with a time difference can be prevented. Hence, interlaced data such as a moving image can be smoothly displayed on a noninterlaced scan display device such as a CRT, LCD, or the like.
As the interlaced data of the predetermined color, relatively dark color data (e.g., black) or equivalent is preferably used, since it hardly influences an image of the input interlaced data. Especially, since black data becomes the color of the screen in a non-display (blanking) period, the influence on the image of the input interlaced data can be minimized using black data as dummy data.
Also, according to the present invention, an apparatus for displaying display data written in a video memory on a display device capable of noninterlaced/interlaced display, comprises a port for receiving interlaced display video data from an external source, means for switching a display mode for controlling the display device from a noninterlaced display mode to an interlaced display mode when the interlaced display video data input from the port is displayed, and means for outputting the interlaced display video data received from the port to the display device.
In this apparatus, interlaced data such as a moving image can be displayed on the display device such as a CRT with high quality without deteriorating the video quality due to interlace to noninterlace conversion.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.